Delreux examines how the EU functions when it participates in international environmental negotiations. In particular, this book looks at the internal EU decision-making process with regard to international negotiations that lead to multilateral environmental agreements. By studying eight such decision-making processes, the book analyses how much negotiation autonomy (or 'discretion') the EU negotiator (the European Commission or the Council Presidency) enjoys vis-à-vis the member states it represents and how this particular degree of discretion can be explained. The book's empirical evidence is based on extensive literature review, primary and semi-confidential document research, as well as interviews with EU decision-makers. It is aimed at a readership interested in EU politics and decision-making, global/multilateral governance, environmental policy science and methodological development of Qualitative Comparative Analysis.